Random Missfire or Bad mas?

[Kash]

So heres the deal, cars a 2g with a 6bolt swap and the potentiometer mod done to it otherwise its stock. Now to get to the problem pretty much any time i go 50-100% wot the car will buck and miss and ill half to let off the gas. Same scenario if you just ease into the gas the car will pull hard. 2nd part of the problem, the car was throwing the code for the maf sensor, uplugged everything sprayed it out with maf cleaner and everything seemed to work great for a week or so but the problems back.

 

[PieEyedPiper]

Have you tried undoing the potentiometer mod?

 

[dsmmike50t]

Check out the link below 1g in a 2g, they have some solutions for misfiring when throwing in a 6 bolt.



Magnus Motorsports

 

[Kash]

i have read it, and ive installed the pot mod.

 

[Kash]

Have you tried undoing the potentiometer mod?

ive turned it off before and it runs like crap threw all the gears with it off, its just hard to figure out since it doesn't throw the random misfire all the time.

 

[TiradoCC]

My friends car is doing the same thing. Doesn't the pot mod just turn off the check engine light?
Or should it get rid of the random misfire?

 

[Kash]

My friends car is doing the same thing. Doesn't the pot mod just turn off the check engine light?
Or should it get rid of the random misfire?

It should stop it from throwing the random misfire, but im not really sure if im missing because of the 6 bolt swap or if its my maf taking a shit.

 

[architechnik]

It sounds like there's not the right amount of air, just as you stated the mas. The other possibility is dirty injectors or low fuel pressure. Have you tested these?

If the vac line going to the fpr is leaky it might not be registering the rapid change in boost as well. Or it could be a vac issue all the way around.

 

[Kash]

It sounds like there's not the right amount of air, just as you stated the mas. The other possibility is dirty injectors or low fuel pressure. Have you tested these?

If the vac line going to the fpr is leaky it might not be registering the rapid change in boost as well. Or it could be a vac issue all the way around.

No, i haven't checked the injectors or the fpr. Its just so damn weird because sometimes the car pulls hard as shit wot and its wonderful, and then the other half you can't even give it 50% throttle because it will make it miss. Btw the codes it was throwing before are p0443 evap, and p0105 for the map sensor.

 

[architechnik]

I'm not familiar with the codes for a 2g, although the map would suggest a vac/boost pressure error and the evaporator system might be the canister leaking or the solenoid not working correctly.

As far as intermittent occurrence, is there any noticeable factor when this occurs? Temperature of oil/coolant, duration engine has been running, ambient temps, dark outside (lights running)... anything on this first list look familiar?

Do you have a logger that you can check the TPS sensor or the ECU readings for any of the sensors? It could be that you've a loose connection on one of these plugs as well.

 

[Kash]

as far as the evap goes, there is none previous owner mod.

 

[turbomoe]

dude my car does the same extact thing! i dont no what it is.. but all i no is that my vacume used to be at 20, and ever scence this happened its been at 14

 

[romeen]

Start with the basics. Do a boost leak test and check plugs and wires.

 

[Kash]

Start with the basics. Do a boost leak test and check plugs and wires.

The plugs and wires are fine, and there are no boost leaks. The question is it just the random misfire from the 6bolt, or is my mas taking a shit on me as well.

 

[Kash]

Yours sounds like a boost leak, do a test and make sure you check around the intake manifold, and the throttle body for leaks.

 

[Kash]

anyone else have thoughts?

 

[turbogabe03]

well i think the POT mod will get rid of the missfire and the CEL because what it does is it changes the values of the barometric press sensor. I read that when the computer sees certain values from tps, coolant tem sensor, and barometric press sensor for a certain amount of time it will start missfiring(on 6-bolt swaps). I think hes got another problem besides that like bad plugs or wires because i had the same problem that i could ease on to WOT and it would be fine but when i would step on it it would buck real hard. I changed the plugs and it was all good.

 

[Spyder4g64]

Unplug your TPS sensor completely and go for a ride..

If the problem is fixed, then it's just the common problem that the 6-bolt in a 2g has.

If it doesn't, then it is something else.

Post back, as I have the remedy if the TPS unplugged solves it.

 

[vancitydsm]

i put money on plugs, or wires

 

[Turbo Talon DL]

I logged a random missfire again today this afternoon when i was at a stop sign exiting a parking lot from a stop. I was at 2000ish rpm and it missed a few times then never did it again. I had 355* coolant temp and 255 counts of knock.WTF I know if either of these two conditions were real and not just imagined, I wouldnt even have an engine in the car to speak of. This has happened several times before but it comes and goes. I always check for DTCs when it happens and nothing shows up. I had it throw a DTC for the ignition coils back in October and corrected that problem. Im starting to think this may be a serious ECU problem or my old style SAFC could be causing a problem, but I cant remove it right now. I'd give out pseudo-reputation points if possible. Thanks. I do accept PMs if you believe this requires a long drawn-out explanation.